Voltage regulator for battery charging system



R. J. AUST April 15, 1952 VOLTAGE REGULATOR FOR BATTERY-CHARGING SYSTEMFiled Nov. 17, 1948 d :7 u? /u 7 Z 7 M Patented Apr. 15, 1952 VOLTAGEREGULATOR FORv BATTERY- CHAR-GING SYSTEM Robert J. Aust, Indianapolis,Ind., assignor to P. R. Mallory & Co., Inc., Indianapolis, Ind., a

corporation of Delaware Application November 17, 1948, Serial No. 60,495

This invention relates to an electrical generating system and, moreparticularly, to a combined voltage and current regulating system forelectric generators associated with a storage battery or other loads.

Observation of present type automotive regulators has shown that in theoperation thereof the regulator contacts operate at a point of extremelylight contact pressure and very small deflections. This has resulted inerratic results since very slight transfer of material or oxidation maycause improper functioning of the regulator. This has also limited theamount of field current that could be successfully controlled toapproximately two amperes. In addition, life tests on such regulatorsshow that even with contacts of especially chosen materials,satisfactory performance of all contacts is not assured.

Therefore, a principal object of this invention is to solve the abovementioned problems.

Another object of this invention is to provide an electrical generatingsystem in which both voltage and current control thereof is obtainedwithin broad limits and satisfactorily held through a substantially highfrequency vibratory relay system.

A further object is to provide a combined voltage and current responsiverelay adapted to carry heavy field currents.

A still further object of this invention is to provide a voltage andcurrent regulating system in which the high field currents thereof arecarried by the heavier contacts.

Still another object is to reduce contact activity at the voltagesensitive element controlling contacts thereby increasing their life andreliability.

Other objects of the invention will be apparent from the followingdescription and accompanying drawing taken in connection with theappended claims.

The invention accordingly comprises the featuresof construction,combination of elements, arrangement of parts, and methods ofmanufacture referred to above or which will be brought out andexemplified in the disclosure hereinafter set forth, including theillustrations in the drawing, the scope of the invention being indicatedin the appended claims.

In accordance with my invention, the current regulating stage of thestandard regulator for a generating system used in charging storagebatteries is provided with a voltage coil and is made the so calledpower relay. This relay is made sufiiciently fast to follow the pulsesreceived 9 Claims. (01. 320-33) from voltage regulator or voltagesensitive element contacts. The voltage regulator element of thestandard regulator is retained using the same magnetic structure andtemperature compensated coil. The armature therefor is reduced in sizeand mass and is operated with a smaller magnetic air gap to increase itssensitivity.

The voltage regulator contacts close when the generator voltage exceedsa desired value thereby causing the power relay coil to be energized.Hence, the power relay contacts are opened reducing the field currentand generator voltage which action, in turn, causes the voltageregulator contacts to reopen. This cycle is continuously repeated aslong as the above condition exists. The combined sensitivity of thevoltage regulator and the speed of the power relay provide sufficientlyfast operation to give smooth and sensitive regulation over the workingrange.

Current regulation is not affected by the voltage coil since the instantthe current regulation begins, the voltage regulator contacts open andthe power relay voltage coil is not energized. The contacts of the powerregulator are normally closed and the spring bias against a movablecontact is adjusted with reference to the ampere turns of the currentcoil so that at a predetermined high current the unit functions as anormal current regulator. As a power relay, the voltage coil on thisunit has sufiicient ampere turns to actuate the armature when thevoltage regulator contacts close.

Basically, the above system of voltage and current control for a batterycharging system retains the inherent sensitivity of the known typeregulator by using the voltage actuated relay whose armature functionsto open and close contacts which operate the voltage coil of theauxiliary or power relay. By proper design of the power relay, thecurrent drawn by its coils and, therefore, that required by the voltageregulators or voltage sensitive relays contacts is of the order of .1 to.2 ampere, which is below the value where silver or silver alloy typecontacts tend to transfer or erode to any appreciable extent.

The power relay contacts are arranged to make and break the fieldcurrents. To accomplish this in a more reliable manner than conventionalregulators requires that the power contacts substantially make and carrythe field current at higher contact pressure and break or open the fieldcircuit with a faster rate of separation than is possible withconventional regulator designs. These requirements call for a high speedtype relay, since for larger contact motion, the faster the armaturemust move to traverse this distance if the power relay keeps fully instep with the pulses received from the voltage regulator element. If thepower relay does not keep in step with the voltage regulator contactpulses, then the system overshoots, resulting in larger generatorcurrent variations at slower intervals, causing objectionablefluctuation of the charge rate indicator or ammeter on the instrumentpanel.

I have found that suificiently fast operation-or pulse frequency can beobtained without too much difiiculty by limiting the motion of thepowerrelay contacts to approximately .010" and reducing the armature mass ofthe power relay and increasing the sensitivity of the voltage sensitiveelement relay. Pulse rates of approximately 15 to 20 cycles per secondundernormal regulating conditions can be obtained, and the ammeterfluctuation does not exceed that normally obtained under same testconditions with conventional regulators.

In order to save thecost'of a fourth or power relay element added to'aconventional regulator, now employing a voltage regulator relay, acurrent limiting relay and a cut-out relay, I have found'itentirelyfeasible to combine the-functions of the power relay with that of thecurrent limiting ralay without any interaction of their functions.

In the drawing:

The single figure of the drawing is a diagrammatical representation ofthe preferred embodiment of the present invention.

As illustrated in the drawing, a controllable source of power Illwhich,in the present instance, comprises a shunt type generator havingan armature shunted by a field winding l2 biased or loaded by animpedance I3 of the resistance type preferably is utilized to transmitelectrical energy to a load such as a battery I4 through a number ofrelays to be described in detail hereinafter. Coupled to the generatoror controllable source of energy In there is found a voltage responsiverelay l5 having a coil; wound on a core I! adjacent to one end ofwhich'is a vibratory type armature l8 preferably of the high frequencytype. In the drawing, the vibratory reed |8arranged for bridging a pairof contacts 2| and 22 normally open is shown pivoted about a point i9and biased by a spring 20 the latter being shown for the purpose ofbetter illustrating the resilient property of the vibratory reed. Ofcourse, the spring 29 may be eliminated and incorporated in the reeditself. The regulator l5, as stated heretofore, is one of the well knowntype and, therefore, need not be described in all details. The contacts2|, 22 normally held open and arranged to be bridged by the vibratoryreed l8 are of substantially small mass to facilitate the desired highfrequency movement of the reed.

A cut-out relay 25 is coupled to the battery it which is grounded at '26in a conventional manner. The relay 25 includes 'thewindings 21 and28preferably wound in a bifilar relationship on the core 29, both beinggrounded as at 36. These windings when energized 'motivatea vibratoryreed or armature 3| preferably of the high frequency type which ispivotally mounted as at A5. the others described above are of ratherheavy 36 is interposed between the voltage relay l5 and the cut-outrelay 2-5. The relay 38 includes two coils 31 and 38 preferably wound ina bifilar relationship and in an additive magnetic sense upon the core33 adjacent to one end of which is pivotally mounted at 4| a vibratoryreed d2 having a contact 43 on one end thereof. "The reed or armature 62is resiliently retained in such position by the spring 44 that contactis normally made between the contact 63 and a fixed contact The contacts43 and 45, as contrasted with construction to carry the heavy loadcurrents of the generating system for a purpose to be more clearlydescribed hereinafter.

Tracing the current flow from the armature II of the generator l8through brushes 5B and 5|, it will be seen that there are a plurality ofcircuits all being grounded at 52 from the brush 5|. The electromagneticwinding I6 of the voltage responsive relay I5 is connected in parallelwith the armature |,'the coil it of the relay being grounded at 53.Another circuit from the armature starting from the brush 53 includesthe field winding l2, normally closed contacts 43 and 45, reed arm i2and the ground as, the latter described circuit from the point 55 on oneend of the field winding |2 producing a shunt or short-circuit aroundthe resistor l3 which is grounded at'56 and is in series with the fieldl2. Still another circuit from the brush 59 of the generator Itcomprises the conductor 57 adapted to carry heavy currents, the winding38 of the dual coil relay 3B, the current winding 23 and the voltagewinding 27 of the cut-out relay 25 grounded at 39. The latter circuit isadapted to close the contacts 32 and 35 upon the voltage of the batteryIt and the voltage of the generator ||l having reached a predeterminedrelationship and functions in a well known manner. -A further circuitoriginates at the brush 50 and includes a portion of the conductor 5?,the

ated in the winding 31 upon the contact 2| and 22 being opened tothereby protect the contacting faces of the contacts. Additional meansto avoid the effects of transients upon the various contacts of theabove described relay and brush contacts 5B and 5| of the generator l0comprises a load such as a resistance Glacross the field l2 of thegenerator iii. The invention also contemplates the use of a rectifier inshunt with the field I2, 'for'the purpose of further suppressing thearcing tendency of the power relay contacts.

Ithas 'also'been found that a dry disc rectifier such as of themagnesium copper sulphite type connected in shunt withthe 'power relayelement contacts 43 and 45 is very effective for higher field currentare suppression.

In the operation of the present battery charging system, the generatorHi is driven by any suitable driving means such as an automobile engine.When the speed of the generator reaches a value such that the outputvoltage is sufiicient,

sufficient to attract the armature and move that arm against the biasingforce of the spring 33 to effect engagement of the contacts 34 and 35and close the load circuit so that the voltage is applied to the load orbattery I4 by the generator I0. When the contacts 34 and 35 are closedthe load current flowing through the generator to the load flows throughthe electromagnet winding 28 to hold or look the arm 3| in the contactclosed position so that variations in the generator voltage will notpermit the release of the arm 3I and disengagement of the contacts 34and 35 unless the generator voltage drops below a predetermined value.Assuming normal operation when neither output voltage nor output currentare excessive the field winding I2 is directly grounded through thenormally closed contacts 43 and 45 of the combined power and currentrelay 36. When the voltage of the generating system reaches the desiredvalue the voltage responsive relay I5 closes its contacts 2I and 22.This action, in turn, energizes the winding 31 of the relay 36, thecircuit being from the hot, side or brush 50 of the generator I 0, andincluding the winding 31 or relay 36, closed contacts 2I and 22 of thevoltage relay I5 and ground 53. The relay 36 will open its contacts 43and 45 and thereby interpose the resistance I3 which may be in theneighborhood of 30 ohms in series with the generator field winding I2,thereby reducing the output voltage of the generator to a proper value.The value of resistance I3 being such that at maximum generator speed; asafe charging current is maintained. It will be noted from the aboveoperation of a battery charging system that the contacts 2| and 22 donot carry the heavy field currents of the generator system but merelyclose a circuit through the winding 31 containing suflicient turns foroperating a rather heavy contact 43 which does carry the field currentof the generator.

When the load current to the battery I4 becomes excessive the currentflowing in the circuit from the brush 50 of the generator through coil38 of the relay 36, the coil 28 of the cutout relay 25, closed contact34 and 35 of the latter relay, battery to ground is suificient to openthe relay 36 to break its contacts 43 and 45. This will likewiseinterpose the resistance I3 in series with the field Winding I 2 therebymaintaining the output current of the generator to a proper value.

The constants of the current regulator portion including the winding 38of the relay 36 such as the normal ampere turns thereof and the normaltension of the spring 44 and also the value of the resistance I3 arepreferably chosen so that under the normal operating conditions of thesystem the arm 42 vibrates and thus intermittently or periodically shortcircuits the resistance I3. That is, when the electromagnetic force ofthe current coil 36 becomes suificient it attracts the reed 42 todisengage the contacts 43 and 45. This disengagement of the contacts 43and 45 opens the short circuit across the resistance I3 to efiect areduction of the current in the shunt field winding I2. This reductionof the exciting current sufiiciently decreases the generator outputcurrent to reduce the magnetomotive force of the winding 38 to a valuethat permits the spring 44 to return the reed 42 to its normal closedposition and effect engagement of the contacts 43 and 45. When thecontacts are thus reengaged, the field current to the exciting windingI2 is again increased. This operation preferably occurs and reoccurs inrapid erator.

It will be evident from the above description that the reed 42 of thecurrent limiting and power relay 36 is arranged to be responsive to thetotal output current of the generator I0 and the actuating pulses fromthe voltage coil 31 in series with the contacts 2I and 22 in the voltageresponsive relay I6. The voltage coil 31, as mentioned heretofore, hassufficient ampere turns so that when the contacts 2I and 22 are closedit causes the armature 42 to rapidly open the contacts 45 and 43 inseries with the generator field I2 regardless of the current level inthe series current coil 38. The relay 36 is adjusted to function as anormal current regulator by adjusting the armature or reed bias springpressure versus magnetic attractive force of the current coil 38 to thedesired maximum current value.

Summarizing, the invention, it is recognized that I have provided aregulating system for a generating system particularly associated withbattery charging in which the voltage responsive relay I5 is capable ofhigh sensitivity and high speed operation but handles only low currents.This voltage sensitive relay I5 actuates the second or power relay 36which is capable of handling heavy field currents since it is positivelydriven through a substantial displacement by means of winding 31, therelay may have heavy contact pressures suitable for operating in thefield coil circuit of the generator without any difficulty. Thus, I haveprovided a regulating system in which the requirements of obtainingsensitive, accurate and smooth regulation have been harmonized with theadditional requirement of handling heavy field currents with reliablecontact performance.

While the present invention, as to its objects and advantages, has beendescribed herein as carried out in specific embodiments thereof, itisnot desired to be limited thereby but it is intended to cover theinvention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. An electrical generating system comprising a controllable sourcehaving a biasing impedance, a load, a cut-out coupled to said load whenapredetermined voltage relationship between said source and the latter isattained, a voltage responsive regulator including normally opencontacts coupled to said source, said regulator including a coilconnected to one of said open contacts, said other contact being fixed,and a two coil regulator including a pair of normally closed contactsand being responsive to both voltage and current respectively said twocoil regulator being interposed between said cut-out and said voltageregulator, one coil of said two coil regulator being connected to saidfixed contact and thus to said source through said normally opencontacts upon a predetermined voltage energizing said voltage responsiveregulator, said normally closed contacts completing a circuit in .shuntwith said biasingimpedance whereby said source can be controlled inaccordance with the position oi said normally closed contacts, the othercoil of said two coil regulator being adapted to carry load currentwhereby saidregulator acts to limit the load current to a predeterminedmaximum value independent of said voltage responsive relay.

2. An electrical generating system comprising, in combination; avariable speed generator having a shunt exciting winding; a load; relaymeans for controlling the voltage and current of :the

generator, said means including a combined power relay and currentregulator coupled to said load, a voltage responsive relay coupled tosaid combinedrelay and said generator field, said voltage responsiverelay including an armature and a pair of normally open contacts, withsaid armature connected to one of said contacts, said power relay beingconnected to said other open contact and responsive to the operation ofsaid voltage responsive relay upon the latter being impressed withpredetermined voltages in accordance with changes of generatorspeed'beyond a predetermined amount, and a resistor normally beingshunted by said combined power and current regulator contacts.

between said dynamo and dual relay and having an armature arranged withcontacts intermittently closing a circuit'coupled to the voltageresponsive coil of said dual relay, one coil of said dual coil relayconnected to one of said latter contacts, and a cut-out interposedbetween said dual coil relay and said battery for closing a circuitthrough thecurrent responsive coil of said dual relay upon apredetermined voltage equal to the minimum level of said voltage levelsbeing reached.

4. An electrical generating system comprising, in combination, agenerator having a shunt field winding; a load; and means forcontrolling the voltage of the generator, said means including aresistance in series with said field winding and at least two relayseach having a vibratable armature, one of said relays' having a contacton said armature and also having a contact which is fixed, said relaybeing responsive to voltage changes about a predetermined level to causea vibration of the armature thereof with an amplitude and frequencydependent on the magnitude of said voltage changes about saidpredetermined *ievel, another of said relays including both'voltage andcurrent coils, said voltage coil of said latter relay being connectedto'said fixed contact of said voltage responsive relay, the voltage coilof said another relay being activated through the response of thearmature of said one relay, the current coil of said another relay beingcoupled in series with said generator, the armature of saidanother'relay in the unattracted position thereof forming a shunt patharound said resistance whereby the voltage of said generator is loweredupon the energization either of said voltage coil of said another coilin response to said predeter- 'minedvoltage changes in said one relayor. of the ::;current changes: in said ;.another coil alone, the

18 said relays being so further arrangedas tomake said one relayinactive in effect uponsald current coil alone motivating its associatedarmature.

5. Aregulating system for an electrical battery charger including agenerator of the shunt field type comprising a first voltageregulator.including a coil coupled to the armature of said generatcr andresponsive to voltage changes abouta predetermined value, a secondregulator including a voltage/coil and a current coil coupled to saidvoltage regulator and responsive upon initiation of said voltageregulator, ,a .cut-out relay including a voltage coil and current coilcoupled to the current coil of said second relayandinterposed betweenthe latter and said battery, and an impedance coupled to said shuntfield in series therewith upon the initiation of saidsecond regulator,to thereby lower the voltage-.outputof said generatonsai-d cut-outrelay'when activated providing a current path through the current .coilof said second regulator, said second regulator being responsive tocurrentchangesabove a predetermined value to thereby place saidimpedance again in series with said field, said impedance and saidvoltage regulator coil being parallel to each other when the voltageregulator becomes unresponsiveduring the timesaid second relay ismotivated by said current changes.

6. .An electrical generating.systemcomprlsing a variable speed generatorhavingan armature and a shunt fleldwinding, a load, voltage responsivemeans including a set of contacts, one of which is fixed to an armaturemovable in response to voltage changes at said generator about apredetermined value and the other of which isalways fixed, a cut-outcoupled to said load, regulator means interposed between said cut-outand said voltage responsive means and adapted for handling heavycurrent, said-regulator means including a voltage coil directlyconnected to said always fixed contactand in series with said set ofcontacts upon said predetermined value of generator voltage beingreached whereby said regulator means is dependent upon said voltageresponsive means in iproducting voltage regulation, said regulatingmeans also including a current coil in series with said cut-out and saidarmature whereby current regulation is produced without said voltageresponsive means, and a resistor normally in series with said generatorfield, said resistor being shunted by said regulator means during saidvoltage and current regulating periods.

7. A regulating system for a battery charger of the generator typehaving a shunt field, comprising a first relay including a coil inshuntwith-said field and a vibratable armature forbridging a set ofcontacts, one of said contacts being fixed and the other on saidarmature, the frequency ofsaid armature being proportional to thevoltage output of said generator versus the battery voltage; a secondrelay including both voltage'responsive and current responsive coils,the voltage coil thereof being connected in parallel with thecoil ofsaid first relay through said set of contacts, said voltage coil beingconnected to said fixed contact, said second relay including avibratable armature for bridging a set of contacts normally closed whenthe generator voltage is below a predetermined value; a resistor inseries with'said shunt field when said normally closed contacts areopened; and a third relay'including both volt age and current coils andan armature carrying a contact for engagement Withafixed contactof saidrelay, said third relayfunctioning. asa -cutout interposed between saidbattery and said second relay, the current coils of said second andthird relays being in series whereby said first relay so assists in thecontrol of the battery charger that only the set of contacts in thesecond relay are subjected to heavy field current.

8. In an electrical generating system wherein a storage battery ischarged by a shunt-armature type generator through a cut-out device, thesubcombination comprising a vibratory reed type voltage regulator with avoltage coil, said regulator including a contact on said reed and afixed contact, a combined-voltage and current responsive regulator ofthe vibratory reed type with two coils coupled additively, oneof saidtwo coils being directly connected to said fixed contact and to the reedof said voltage regulator upon the latter being impressed with apredetermined minimum voltage, the fother of said two coils beingcoupled to said armature in series therewith whereby said combinedregulator is made responsive to current beyond a predetermined maximumvalue independent of said voltage regulator, and field current-limitingmeans coupled to the field of said shunt generator, said field currentlimiting means being shunted by the vibratory reed of said combinedregulator when either the voltage across the battery or the currentthrough the generator is lower than a predetermined value.

9. In an electrical generating system wherein a shunt wound generatorhaving a substantially high current carrying capacity armature is usedto charge storage batteries protected by a cut-out and a voltageregulator of the vibratory reed type 10 having relatively light contactsnormally open when the voltage on said regulator is below apredetermined amount, one of said contacts being on said reed and theother fixed, the subcombination comprising a two-coil-single-core woundregulator including a vibratory reed arranged for intermittentlyconnecting contacts adapted to carry substantial current and beinginterposed between said cut-out and voltage regulator, one of saidlatter coils being connected to said fixed contact of said voltageregulator with said intermittent contacting being dependent either on aclosed position of said normally open position of the contacts of saidvoltage regulator to effect voltage regulation or on a predeterminedcurrent density through one of said two coils independent of saidvoltage regulator.

ROBERT J. AUST.

REFERENCES CITED The following references are of record in the file ofthis patent:

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